You are currently telling him that it should increase it's opacity when under 99%, and decrease when over 1%
At 100%, it ll decrease 2% before getting inbetween (98%), where it is both under 99% and over 1%, thus applying both the addition and substraction of opacity, which is not the desired effect
I guess a better way to handle that would be to have logofade being equal to -1 or +1, and adding it to the current opacity.